The need for amino acids in nutrition, pharmacy, industry and science is increasing. Raw materials for their production are protein substances such as gelatins, casein etc., which are broken down to their building blocks by enzymatic or acid hydrolysis. The amino acid mixture thus obtained is separated into defined amino acids by known methods, using ion exchangers in conjunction with the means of classical chemistry. This "classical" production of amino acids is encumbered with the costs associated with the raw material (protein) and the cost of its hydrolytic cleavage to the amino acid mixture.
On the other hand, the sugar beet appears to be an inexhaustible and cheap but hiterto virtually unused source for the production of amino acids, because in it the amino acids are already present as such. In the diffusion process, that is, in the extraction of the sugar beet for the recovery of sugar, they pass into the raw juice without having caused any costs. The raw juice is turbid and unfiltrable due to the presence of cell debris. Furthermore, it contains colloids, proteins, pectin and saponin, which must be removed.
To the sugar technician, amino acids represent undesirable nitrogen. Upon the concentration of the sugar juices, they combine with the invert sugar naturally present in the sugar beet to form dark discolorants. Glutamine is especially undesirable: it becomes transformed to pyrrolidone carboxylic acid ammonium which loses its ammonium ion at the boiling temperatures, thereby making the juice acid. This in turn brings it about that sugar (saccharose) is transformed to invert sugar, which then again reacts with amino acids to form dark discolorants. Sugar loss, more difficult crystallization, poor sugar quality and a higher production of molasses are the undesirable consequences. The declared purpose of the main liming operation is therefore the destruction of the acid amines, such as glutamine and asparagine, and of the invert sugar naturally present in the raw juice. The amino acids, which ultimately remain intact, reappear in the molasses where they still represent some value as animal feed. Also, approximately 15% of the sugar originally contained in the raw juice will be contained in the molasses.